1. Field of the Invention
The invention relates to a spring strut for vehicles, and more particularly to a spring strut having noise reduction.
2. Discussion of the Prior Art
Such noise-reducing supports between the coil spring and the spring-plate are known from European reference EP 0 733 824 A1 and German reference DE 40 07 488 A1. These flexible pads are produced as three-dimensionally twisted moldings and are expensive due to the involved production process. Positionally correct mounting of the flexible pad is likewise not assured because of the absence of precise position marking, which means that the flexible pad has to be made considerably larger and, accordingly, with a higher outlay on materials.
German reference DE 196 32 184 A1 reveals a connection between the flexible pad and the spring-plate. The flexible pad is provided on its outer edge with axially directed spring tongues which allow the pad to be attached to the spring-plate and, in the process, engage behind the spring-plate. In all these embodiments of the flexible pad, a molding of varying axial extent is used and, because of the amount of material required, it is relatively heavy. The molding and the, to some extent, unnecessary volume of material furthermore result in high costs in terms of production and materials.
Accordingly, it is an object of the present invention to provide a flexible pad which can be produced at reasonable cost and allows positionally correct connection to the spring-plate without any problems.
Pursuant to this object, and others which will become apparent hereafter, one aspect of the present invention resides in the flexible pad being a component of disk-shaped design which is flat on both sides. The pad is connected to the spring-plate by means of form-locking engagement using at least one projection and at least one aperture. The flexible pad is adapted to the surface of the spring receptacle of the spring-plate by the prestressed coil spring. The simple disk-shaped design of the flexible pad allows production at very reasonable cost. Compared with the known flexible pads, for instance, a smaller volume of material is required and, accordingly, high-grade and expensive material is saved. This disk-shaped flexible pad can, for example, be produced by cutting it off a correspondingly designed molding. As an alternative, the flexible pad can be produced from slabs of desired thickness, e.g. by water-jet cutting. By appropriate choice of material and appropriate thickness of material, it is possible to mitigate or eliminate noises stemming from the spring strut, vibration and other unpleasant characteristics. The flexible pad can accordingly be composed of a very wide variety of materials, such as rubber, PU or some other flexible plastic. The avoidance of unnecessary thickening of the material on the flexible pad provides a low-cost component of low weight. In the case of the flexible pad, the projections and/or apertures required for positionally correct assembly are made in the plane of the disk, while the apertures and/or projections on the spring-plate which interact with it do not require any extra expenditure, or at least no significant extra expenditure, during its production as a formed and embossed part.
According to another embodiment of the invention, the flexible pad has a projection which is formed by an inward-pointing tongue which engages in a corresponding aperture in the spring-plate. A form-locking point of connection of this kind can also be formed by arranging in the tongue an aperture which engages in a corresponding projection of the spring-plate.
A further point of connection between the flexible pad and the spring-plate is created by the flexible pad having an aperture which is formed by an elongate hole, the spring-plate projection interacting with the elongate hole so as to simultaneously form an anti-rotation safeguard for the coil spring. By means of the elongate hole, it is possible to compensate for the manufacturing tolerances which arise during the production of the spring-plate, and moreover an undersize of the width of the elongate hole results in an axial retention force between the flexible pad and the spring-plate. This is particularly important when the spring struts are being transported to the vehicle manufacturer with the spring-plate but without the coil spring, ensuring that the flexible pad is held accurately on the spring-plate, even when roughly handled during shipping.
In accordance with the features specified, another advantageous refinement of the subject matter of the invention is obtained if the inward-pointing tongue of the flexible pad is provided with lugs which extend in the plane of the disk and, as the tongue-shaped projection is pulled into the aperture in the spring-plate, come to rest by retention surfaces against the rear side of the spring-plate. This form-locking point of connection is accordingly particularly well secured against release by virtue of the fact that the flexible pad is clipped into the spring-plate. With such a connection, the aperture in the spring-plate can be chosen so that assembly is facilitated by twisting the tongue with the lugs and inserted without any significant expenditure of force. The latching connection is effected by the tongue springing back into the initial position and the retention surfaces of the lugs thus coming to rest against the rear side of the spring-plate.
As a further means for positionally correct assembly of the flexible pad with the spring-plates, the flexible pad is provided with, in one region of the inner circumference, a bearing surface which is arranged so as to rest against the outer surface of the container.
In the region of the spring receptacle, the flexible pad can furthermore be provided with one or more apertures or clearance cuts, which keep free openings in the spring-plate or channels between the spring-plate and the container, these openings being intended, for example, to allow water to drain off.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.